Democratic presidential nominee former Secretary of State Hillary Clinton (L) speaks as Republican presidential nominee Donald Trump looks on during the town hall debate at Washington University on October 9, 2016 in St Louis, Missouri. (Photo by AFP)

Republican and Democratic presidential nominees Donald Trump and Hillary Clinton attack each other with brutal exchanges during their second presidential debate a month before the Election Day.

The debate was held at Washington University in St Louis, Missouri, on Sunday night.

The two candidates broke traditional debate decorum by refusing to shake hands as they took the stage.

Trump called her Democratic rival a "devil" and Clinton said the business mogul owes all Americans an apology for a campaign driven by insults and degrading comments about women and minorities.

The debate came as the Trump campaign is in crisis after his sexually obscene comments, made years earlier, were exposed in a video tape.

The video was recorded in 2005 while Trump was on a bus with former "Access Hollywood" host Billy Bush. The former reality TV star can be heard talking about his failed attempt to seduce a “married” woman. "I moved on her and I failed. I'll admit it. She was married. And I moved on her very heavily." He also says, “I’m automatically attracted to beautiful” women. "I just start kissing them. I don't even wait. And when you’re a star, they let you do it. You can do anything.”

The leaked tape angered Republican leaders, many of whom have withdrawn their endorsement of Trump and called for him to drop out of the race.

According to the Associated Press, the debate served as Trump’s “final opportunity to keep his campaign.”

Commenting on his lewd remarks exposed in the recording, Trump pushed back against the criticisms, saying he had never really kissed or groped women without consent and that was just "locker room talk."

"No, I didn't say that at all. I don't think you understand what I said," he told debate moderator Anderson Cooper, who described the remarks as “sexual assault."

Clinton, on the other hand, rejected Trump’s defense in his apology following the leak, saying the vulgar comments reflect "who Donald Trump is" and what he "thinks about women, what he does to women."

"It's clear to anyone who heard it, it represents exactly who he is."

Trump is joined by his daughter Ivanka Trump (L) and his wife Melania Trump at the end of the town hall debate at Washington University in St. Louis, Missouri, on October 9, 2016.

She further denounced Trump’s other disparaging remarks against not only women, but African Americans, asylum seekers, people with disabilities, prisoners of war and Muslims.

The former first lady shrugged off Trump’s attacks on Bill Clinton’s affair as US president, and suggested that Trump’s apology was not enough as he must apologize to the whole country for the way he has conducted his insult-driven campaign.

Bill Clinton 'far worse' an abuser

Trump tore into Hillary's husband for his past infidelities and allegations of sexual misconduct.

"If you look at Bill Clinton, far worse," Trump said. "Mine are words, and his was action. His was, what he's done to women, there's never been anybody in the history of politics in this nation that's been so abusive to women.

"So, you can say any way you want to say it, but Bill Clinton was abusive to women. Hillary Clinton attacked those same women and attacked them viciously."

Trump invited three women who have accused Bill Clinton of sexual misconduct to the debate, along with a fourth who is a rape victim and has criticized Hillary Clinton for defending her accused rapist as the court-appointed defense attorney 40 years ago.

"So don't tell me about words," he said. "I absolutely, I apologize to those words. ... When Hillary brings up a point like that and she talks about words that I said 11 years ago, I think it's disgraceful, and I think she should be ashamed of herself."

Islamophobic answer to Islamophobia question

Later during the debate, Trump refused to answer a question about how to stop Islamophobia in the US, asserting that Muslims themselves should report dangerous behavior by terrorists.

The billionaire suggested that American Muslims don’t often share information with law enforcement in order to protect extremists within their communities.

“Muslims have to report the problems when they see them,” he said. “And you know there’s always a reason for everything. If they don’t do that, it’s a very difficult situation for our country.”

Trump also said that his controversial proposal to ban Muslims from entering the US has “morphed” into a plan for “extreme vetting” of refugees who he said might be a “Trojan horse.”

Trump speaks during the debate (Photo by AFP)

Clinton slammed Trump's stance as "dark and divisive."

“We are a country founded on religious freedom and liberty. How do we do what [Trump] has advocated without causing great distress within our country?” the Democrat said. “Are we going to have religious tests when people fly into our country?”

Clinton 'in jail' if I were president

Trump also attacked his Democratic rival over her use of a private email server as secretary of state. The businessman said he would appoint a special prosecutor to investigate Clinton if elected president.

"There has never been so many lies or so much deception, there has never been anything like it...the people of this country are furious," Trump said. “You should be ashamed of yourself.”

The issue of Clinton's emails has been a line of attack for Trump, who repeatedly questioned why the former secretary of state deleted thousands of her emails before turning over her correspondence.

“You deleted them, then you acid washed them,” he said at the debate.

Clinton acknowledged that she “made a mistake,” but said it was good that someone with Trump’s temperament was not in charge of the US legal system.

Trump quipped, "Because you would be in jail."

Clash over Syria policy

In an exchange over Syria policy, Trump said he disagreed with his running mate, Mike Pence, who earlier urged US attacks against military targets of President Bashar al-Assad if Russia continued to assist the Syrian government with airstrikes.

“He and I haven’t spoken and I disagree,” he said.

“You have to knock out ISIS. Right now,” the real estate tycoon said, using another acronym for the Daesh terrorist group. “Syria is fighting ISIS. We have people that want to fight both at the same time.”

“We have to worry about ISIS before we can get too much more involved,” Trump noted.

The Republican candidate said he did not like Assad, but added that his forces were battling terrorism along with Russia and Iran.

“I don’t like Assad at all, but Assad is killing ISIS. Russia is killing ISIS. And Iran is killing ISIS. And those three have now lined up because of our weak foreign policy.”

Meanwhile, Clinton accused Russia of being only "interested in keeping Assad in charge" and not paying "any attention to ISIS."

Hillary Clinton speaks during the debate. (Photo by AFP)

"We need some leverage with the Russians because they’re not going to come to the negotiation table without leverage," Clinton said.

She also renewed her calls setting up a no-fly zone in Syria and arming the Kurdish fighters, but acknowledged that sending US troops on the ground would be “a very serious mistake."

Earlier in the debate, Trump said that the US and Russia should fight Daesh together in Syria. “I think it would be great if we got along with Russia.”